Year	Percent
1998-01-01	37.675
1999-01-01	37.025
2000-01-01	36.075
2001-01-01	35.250
2002-01-01	34.450
2003-01-01	33.600
2004-01-01	33.225
2005-01-01	32.225
2006-01-01	31.725
2007-01-01	31.250
2008-01-01	31.125
2009-01-01	31.150
2010-01-01	30.300
2011-01-01	30.500
2012-01-01	30.275
2013-01-01	30.225
2014-01-01	30.000
2015-01-01	29.650
2016-01-01	29.500
2017-01-01	28.350